Download Chapter 4 - Tolland High School

Chapter 4
Passive Transport
&
Active Transport
Cell Membrane Review:
• Selectively Permeable Membrane- the
cell membrane only allows specific
substances to pass through it
Passive Transport
• Passive transport
moves substances from
higher concentration to
lower concentration
• Passive transport does
not require any energy
(ATP)
Concentration Gradient
• A concentration gradient is a range in
concentration across a space
• Concentrations change from high  low
Equilibrium
• Equilibrium is a condition when the
concentration of a substance is equal in all
areas
Equilibrium
Diffusion
• Diffusion is the movement of molecules
from areas of higher concentration to
areas of lower concentration by random
movement of the molecules
Lower Concentration
Higher Concentration
Osmosis
• Osmosis is the diffusion of water(H2O)
through a selectively permeable membrane
• Water moves to areas with less pure water
and more dissolved solutes(like salt or sugar)
Solutions(review)
• Solute- the substance that gets dissolved
– Ex: salt, sugar, kool-aid, chocolate milk mix
• Solvent- the substance that dissolves
another substance
– Ex: water, alcohol, milk
Types of Solutions
• Hypertonic Solutions- water diffuses out
of the cell
– A higher concentration of solute outside of the
cell draws water out of the cell
– Cells will shrivel and shrink in a hypertonic
solution
Types of Solutions
• Hypotonic Solutions- water diffuses into
the cell
– A lower concentration of solute outside the
cell causes water to enter the cell
– The cells will expand or even burst
Types of Solutions
• Isotonic Solutions- equal movement of
water into and out of the cell
– Equal concentration inside and outside the
cell
– Cells remain their normal size and shape
Transport Proteins
• Proteins stuck in the cell membrane act as
transport tunnels that move substances
into and out of the cell
Ion Channels
• Ion channels are transport proteins that
move positive(+) and negative(-) ions
across the cell membrane
– Ex: Na+ and Cl-
Gated Ion Channels
• Gated Channels can open and close to
allow or prevent ions from passing through
Facilitated Diffusion
• Facilitated diffusion uses carrier proteins
to move substances across the cell
membrane
Carrier Proteins
• How Carrier Proteins Work:
– 1) Bind to a substance
– 2) Change shape
– 3) Release substance on other side of cell
membrane
Active Transport!
• Active transport moves substances across
the cell membrane against the
concentration gradient, from low  high
• Active transport requires energy(ATP)
Sodium-Potassium Pump
• Transports sodium ions(Na+) out of the cell
and transports potassium ions(K+) into the
cell
• Requires ATP(energy) as a form of active
transport
Movement in Vesicles
• Cells use vesicles to transport large
molecules into and out of the cell
– Ex: glucose in & wastes out
Endocytosis
• The movement of large molecules into the
cell
• The cell engulfs the molecule
Endocytosis
Exocytosis
• Movement of large molecules out of the
cell
• Cell releases the substance(waste)
Exocytosis
Endocytosis & Exocytosis
END OF CHAPTER 4 NOTES!!!